Art of setting diamonds for industrial purposes



y 14, 1940- c. .1. KOEBEL 2.200.281

ART SETTING DIAMONDS FOR INDUSTRIAL PURPOSES Filed July 28, 1937 2 Sheets-Sheet 1 43 INVENTOR ATTORNEY May 14, 1940.

c. J. KOEBEL 2,200,281 ART OF SETTING DIAMONDS FOR INDUSTKIAL PURPOSES Filed July 28, 1837 2 Sheets-Sheet 2 INVENTOR ATTORNEY Patented May 14, 1940 2,200,281

UNITED STATES PATENT OFFICE ART OF SETTING DIAMONDS FOB INDUSTRIAL PURPOSES Charles J. Koebel, Detroit, Mich. Application July 28, 1937, Serial No. 15!,223 9 Claims. (Cl. 76-108) Diamond-carrying tools that are now so ina limitation upon the character of the stones that creasingly used in the industrial arts are subject are usable. to great stress and strain. The setting or mount- The main object and feature of this invention ing which carries the diamond must therefore is to overcome these various disadvantages, and hold it with great firmness and must be capable to provide a method whereby inexpensive ma- .5 of resisting the heat generated by the cutting terial can be successfully used to set diamonds of action of the tool against the work acted upon. practically any shape and which requires in prac- Dlamonds, when being set, cannot be subjected ice v y i l pert skill and one which, while to excessive temperatures as that tends to deadmitting of theindividual seating or positionlo stroy the valuable properties of the stones, and ing of a plurality of diamonds on a readily worktherefore processes that involve the production of able carrying member, permits simultaneous seta setting by casting molten metal around the ting of the individually seated stones; and also stone have not been successful to any great exin which the step of hardening the setting is cartent. It has also been attempted to produce a ried on after the diamonds have been individually i5 hardened slug and thereafter to set the diamond positioned and at temperatures well below the II in the slug as by peening the metal'over the stone, critical point at which the character of the stone but this necessarily means that the labor of becomes adversely ailected. peening the hard metal of the setting is very In the accompanying drawings several predimcult and slow and requires highly skillful ferred exemplifications 0f the invention are dis- :9 working. Moreover, to obtain a sufllciently closed, and in said drawings:

strong setting, the stone must have a fairly pro- Fig. 1 is a vertical sectional view of one form nounced girdle or equator so that the metal may of mold for compressing comminuted metallic be worked over it to adequately grip the stone material; and prevent it from coming loose, and this ren- Fig. 2 is a diagrammatic representation of one ders many relatively inexpensive diamonds, that form of sintering furnace that may be used in 25 would otherwise be suitable for the purpose, unconnection with the invention;

fit for use on account of their shape. There is Figs. 3 and 4 are respectively edge and plan still another disadvantage in peening hard metal views of one form of carrying member that may over a stone, and that is a tendency to break the be used in carrying out the invention;

so stone during the process of peening. It has been Figs. 5 and 6 are views similar to Figs. 3 and 4 attempted to overcome this by drilling a relativebut showing diamonds preliminarily positioned or 1y large hole or otherwise forming an aperture seated on the carrying member;

' in a metal slug and filling the hole around the Fig. 7 is a fragmentary detail sectional view diamond with a brazing material, but this too has 01' a portion of a carrying member with two methbeen found unsuitable in that the setting is not ods of seating the diamonds indicated; a strong enough and, in the case of a corebit car- Fig. 8 is a view similar to Fig. 1 but showing ring numerous diamonds, it, as well as the peenthe compressing of an additional body of coming process, requires each diamond to be set inminuted material around the stones that have dividually-necessarily a slow method. In Patbeen seated in the carrying member;

0 ent No. 1,848,182 of March 8, 1932, is disclosed Fig. 9 shows the placing of a body of copper on 0 an invention in which'a diamond is imbedded in a the comminuted material and the assemblage bodyof comminuted metallic material, and there-- laced in a suitable mold for sintering the addiai'ter sintered. This process has been extensivetional bow of comminuted material and hardenly used and is in successful operation today but ing the setting;

when the comminuted material is subjected to Figs. 10 and 11 are views similar to Figs. 5 and 45 pressure the diamond, if its longest dimension ex- 6; but show the finished roduct;

tends inthe direction in which pressure is ex- Figs. 12 and 13 are resectively edge and plan erted when compressing the comminuted material views of 'a difi'erent form of carrying member; before sintering, will naturally. tend to change its Figs. 14 and -15 are views similar to Figs.- 12

position in the material and this is objectionable and 13 but show a coating of paste of comminuted go because the pointed end of such diamond is more metallic material anddiamond particles applied effective as a cutting surface than the more blunt to the carrying member; portion. To overcome this, the use of diamonds Fig. 16 is a view similar to Fig. .14 but shows that are relatively longer in one direction than a body of coppe placed on top of the assemblage 5 in the other is avoided, and this again constitutes of Fig. 14

Fig. 17 is a view similar to Fig. 16 but shows the finished product;

Fig. 18 is a top plan view 01 a muffle that may be employed in place of the mold shown in Fig. 9 for the sintering operation; and

Fig, 19 is a section on the line l9, IQ of Fig. 18. In carrying'out first produce a carrying member that is, with respect to the final hardness of setting desired, relatively soft. The material used can be principally iron, and I have found Swedish iron with a slight admixture of cobalt and copper to be a suitable medium. As an exemplification of the material that can be used the following formula is given:

Per cent Swedish iron 89 Cobalt 6 Copper 5 Preferably the metallic material is comminuted or reduced to powder form of say three hundred and twenty five mesh and thoroughly mixed as by ball milling for one hour. A body of powder 25 is then placed in a mold as 26 provided with a bottom molding die 26 and subjected to a pressure of from twenty to thirty tons by means of a plunger 21 to compress thematerial into a fairly stable body. As the shape of the carrying member to be produced here happens to be ringlike, a center post 28 is carried by the mold to produce the circular opening in the carrying member. The member thus produced, indicated by 29, is then placed in a sintering furnace 30 of any suitable construction and from which air is excluded where it is sintered at a temperature of say 1200 centigrade. One form of furnace that may be employed for this purpose is disclosed in my Patent No. 1,848,182 of March 8, 1932. Carrying member 29 thus produced has shrunk but slightly, about one percent or less, and is readily workable in that it has a hardness of from forty-five to fifty-one according to Rockwell hardness testing device. According to the procedure illustrated in Fig. 1, the carrying member is pressed with a radius prior to the sintering treatment but if desired, said carrying member may be pressed in some rectilinear form and a radius turned thereon after the sintering treatment. After the carrying member is cooled to room temperature, one or more diamonds or diamond particles are preliminarily positioned or seated on said member. Fig. 7 exemplifies this operation, and it will be seen that apertures as 3| and 32 can be readily formed in the carrying member as by drilling and it will be noted that the size and shape oithese apertures can be different so as to suit the size and shape of different stones as 33 and 34. To'hol'd the stone temporarily in position it may be lightly tapped as indicated in connection with 33, the lower end 35 of which is slightly imbedded in the relatively soft material of the carrying member or, as indicated in connection with 34, the relatively soft metal can be peened over as at 36 to retain the stone in position. The particular tool here selected to illustrate the invention is a corebit and, as shown in Figs. 5 and 6, a number of diamonds will be seated on thecarrying member in such relative position as will render the tool most effective. The surface or surfaces that carry the stones are now covered with a body of comminuted material 31 of the same character as the process of my invention 1- that used in forming the carrying member; This body of comminuted material may be either in powder or paste form and, if in powder form, it may be slightly compressed to fill the interstices around the stones, as by placing it in a suitable mold as 38 and subjecting it to the action of a plunger 39 that may be operated by hand. Ii it is desired to use the material in paste form, a slight amount of parafiln can be added thereto, and the paste smeared and packed around and over the stones. A body of copper 40 or other material, as silver solder, having a lower melting point than the comminuted material is now placed on the body of comminuted material 31 and the assemblage thus produced is sintered at a temperature slightly below that used in sintering the original carrying member. I have found a temperature of 11'14 centigradesuitable for this purpose. The result 01 this action is .that the individually positioned stones are set simultaneously and permanently by the creation of a sintered extension on the original carrying member. At the same time. the body of copper or other material insinuates itself through the carrying member and hardens thesetting to about ninety-seven or eight according to the Rockwell hardness testing device. The copper used will preferably be electrolytic copper and I have found a body of copper equal to forty percent by weight of the material used to produce 'the original carrying member gives good results.

I have found that the amount of copper needed depends upon the pressure to which the comminuted material of the carrying member is subjected. The more highly compressed the comminuted material is, the less copper is needed. The sintering can conveniently be carried on in a carbon mold 4| or a graphite boat 46, or other suitable device for the purpose, that can be placed in a furnace like 30. According to the arrangement shown in Figs. 18 and 19, diamondstudded slug 29 is placed upon slabs 41 of alundum in boat 46 after comminuted metal 48 in powdered or paste form has been applied to the diamond-studded surfaces and surmounted by a body 49 of copper or other suitable material, as described above, the complete assemblage being placed in sintering furnace 30. It will be noted that the steps are carried on at temperatures well below the critical temperature, about 1380 centigrade at which the desirable qualities of the diamonds are adversely aflected. The finished product is indicated at 42 in Figs.

l0 and 11 and will usually require some sandblasting to properly expose the diamonds. The

in any suitable manner on a holder, as by brazing, welding or otherwise.

A modification of the above process is as follows. The comminuted metal previously described is compressed under a pressure of from twenty to thirty tons and heated in furnace 3| at a temperature of 950 centigrade, thereby producing a carrying member having a hardness 0! only elevenwith respect to theRockwell hardness testin device. The holes are then drilled and the diamonds preliminarily positioned and a body of comminuted metal of the same character as that used in producing the carrying member is appliedover and around the stones, but no body of copper is applied at this point. The body of comminuted metal is then subjected to a pressure of thirty tons and sintered in a furnace such as 30 at a temperature of 1175 centigrade, thereby setting the diamonds and increasing the hardting'. The diamonds minuted metal of the character I 2,200,281 ness of the carrying member to fifty-five according to the Rockwell hardness testing device. after cooling the setting, a body of copper is then applied to the surface-carrying the diamonds and the assemblage is heated to a temperature of 1174 centigrade, thereby obtaining a hardness of ninety-four or five according to the Rockwell hardness testing device. The advantage of this mode of operation is that there is practically no shrinkage of the setting after it has been sintered at a temperature of l175 centigrade.

" It will, of course, be understood that the invention is not limited to the production of core-.

bits or that, if used bits, it is necessary for the production of coreto produce a ring-like setcan be set in slugs and the slugs mounted in slots or otherwise on a holder as shown, for instance, in my application Ser. No. 121,935, filed January 23, 1937.

In Figs. 12 to 17 is illustrated an abrasive tool in which diamond particles instead of relatively large diamonds are used. In this case a carrying member 43, here in the form of a disk, of relatively soft material is produced as before. A mixture 44 of diamond particles and compreviously described and having a small amount of paraflin is then applied to the surface of the disk as indicated in Fig. 14. The assemblage is then subjected to pressure thereby positioning the diamond particles in the soft carrying member. A body of copper 45 is then placed on the surface carrying the diamond particles and the assemblage is then sintered at a temperature slightly below that initially used in sintering the carrying member. It will be understood that one or more or all of the surfaces of .the carrying member may be'provided with the abrasive mixture described. 1

I claim:

1. The method of setting a diamond for industrial purposes which consists in: sintering a compressed body of comminuted metallic material composed principally of iron having a slight admixture of cobalt and copper to form a relatively soft porous carrying member; preliminarily posltionlng a diamond on the carrying member thus produced; applying to that surface of the carrying member on which the diamond is carried a layer of comminuted metallic material of substantially the same character as that originally used in producing the carrying member; applying a body of copper to the surface of the layer of comminuted material; and subjecting the assemblage to heat ata temperature lower than that used in sintering the carrying member but sumciently high to sinter the layer of comminuted metallic material and to cause the copper to insinuate itself into the carrying. member to thereby harden the latter and set the diamond permanently. I

2. The method of setting a diamond for industrial purposes which consists in: sintering a compressed body of comminuted metallic material composed principally of iron to form a relatively soft carrying member; forming an aperture in said carrying member; seating a diamond in said aperture; applying to that surface of the carrying member on which the diamond is carried a layer of pressing said layer of material and subjecting it to a temperature above that used in producing the carrying member but below the point at which the desirable qualities of the diamond are adversely affected; applying a body of copper to the comminuted metallic material; com

surface carrying the diamond and subjecting it to a temperature above that used in originally producing the carrying member but below that used in heating the layer of comminuted material.

3. The method of making an abrasive tool which consists in producing a relatively soft porous metallic carrying member by sintering a body of compressed comminuted metallic material. coating one or more surfaces of said member with a mixture of comminuted metallic material and diamond particles, applying to said coating a body of metallic material having a lower melting point than that of said coating, and then subjecting the assemblage to heat at a temperature below that used in originally sintering the carrying member but sufliciently high to sinter the comminuted metallic material and to cause'the body of metallic material to insinuate itself into the carrying member.

4. The method of making an abrasive tool which consists in producing'a relatively rigid but relatively soft porous metallic carrying member consisting principally of iron by sintering a body of compressed comminuted metallic material, coating one or more surfaces of said member with a mixture of diamond particles and comminuted metallic material, principally iron, applying a body of copper to said coating and then subjecting the assemblage to heat at a temperature below that used in originally sintering the carrying member but sufficiently high to sinter the comminuted metallic material and to cause the copper to insinuate itself into the carrying member.

5. The method of setting a diamond for industrial, purposes which consists in: producing a relatively soft and porous metallic carrying member by sintering a body of comminuted metallic material; preliminarily positioning a diamond on said carrying member in a layer of comminuted metallic material; applying to said layer a body of metallic material having a lower melting point than that of said layer; and then subjecting-the assemblage to heat at a temperature below that used in originally sintering the carrying member but sufliciently high to sinter the layer and to cause the melting point to insinuate itself into the carrying member, to thereby set the diamond permanently and harden the carrying member.

6. The method of setting a diamond for industrial purposes which consists in: producing a relatively soft and porous metallic carrying member by sintering a body of comminuted metallic material; preliminarily positioning a diamond on said carrying member in a layer of comminuted metallic material of substantially the same character as that originally used in producing the carrying member; applying to said layer a body of metallic material having a lower melting point than that of said layer; and then subjecting the assemblage to heat at a temperature below that used in originally sintering the carrying member but sufllciently high to sinter the layer and to cause the metal having the lower melting point to insinuate itself into the carrying member, to thereby set the diamond permanently and harden the carrying member.

7. The method of setting a diamond for industrial purposes which consists in: producing a relatively soft and porous metallic carrying memmetal having the lower her by sintering a body of comminuted metallic 4 material composed principally of iron; preliminarily positioning a diamond on said carrying 4- member in a layer or comminuted metallic ma terial;--applying to said layer a body of metallic *rmaterial having a lower melting point than that thezmetal having the of said layer; and blage to heat at a temperature below that used in originally sintering the carrying member but sufllciently high to .sinter thevlayer and to cause lower melting point to insinuate itself into the carrying member, to therebyset the diamond permanently and harden the carrying member. v

8. The method of setting a diamond for in,- dustrial purposes which consists in: producing a relatively soft and porous metallic carrying member by sintering a body of comminuted metallic material composed principally of iron; preliminarily positioning a diamond on said carrying member in a layer of comminuted -metallic material of substantially the same character as that originally used in producing the carrying memb r; app yi material having a lower melting point than that of, said layer; and then subjecting the assemblage to heat at a temperature below that used in originally sintering the carrying member but then subjecting the assem to said layer a body oifmetallic sumciently high to sinter the layer and to cause the metal having the lower melting point to insinuate itself into the carrying member, to thereby set the diamond permanently and harden the carrying member. g

9. The method of setting a diamond for industrial purposes which consists in: sintering a compressed body of comminuted metallic material to form a' relatively soit porous carrying member; forming an aperture in said carrying member; seating a diamond in said aperture; applying to that surface oi! the carrying member on I is carried a layer of comminuted metallic material; compressing said layer oi material and subjecting it to a temperature above that used in producing the carrying member but below the point at which the desirable qualities of the diamond are adversely aflected:

applying a body of material having a lower melting point than that of said layer-to the surface carrying the diamond and subjecting it to a temperature above that used in originally producing the carrying member but below that used in heating vthe layer of comminuted material.

I CHARLES J. KOEBEL. I 

